1. Field of the Invention
The present invention relates to indicators, and more particularly to indicators of the integrity or authenticity of an item or its conformance to an original state. In another aspect, the invention relates to a mechanism employing such indicators. In still another aspect, the invention relates to a process for determining the integrity or authenticity of an item or its conformance to an original state, involving the taking of measurements with respect to such an indicator.
2. Brief Description of the Prior Art
Previously known indicators of the integrity or authenticity of an item or its conformance to an original state have ranged from stamps and seals to watermarks, to holographic images or magnetic strips on credit cards, to shrink bands, membrane seals, metal breakaway caps, and blister packaging for food and drug items.
One difficulty with these former indicators is that one who would attempt to counterfeit, alter or tamper with items associated with these indicators is aware of the existence of an indicator, and of the success of the indicator in detecting such attempts as are described. This awareness of the existence and success of an indicator can lead to attempts to duplicate that indicator, some of these attempts perhaps being successful enough to evade immediate detection, and can make identification or capture of the individual counterfeiter or tamperer difficult.
For example, if a tamperer attempts to repair or hide the evidence of his tampering by reconstructing or duplicating a tamper evident, tamper resistant feature and is unsuccessful in doing so, the tamperer may not attempt to return the item to within the stream of commerce, so that the source and magnitude of a tampering problem is concealed from those persons who would be most affected by it and from those who could take corrective actions. In the meantime, the previously unsuccessful tamperer may find success with another item or product in perhaps another location.
With regard to the detection, monitoring and capture of persons engaged in espionage or counterfeiting in particular, the resources which may be available to such persons might be sufficient to reconstruct, duplicate or otherwise negate the presence of the aforementioned indicators. If these indicators are not readily perceived by the senses of sight and touch, for example, then these resources may not be brought to bear and the espionage or counterfeiting activities and persons responsible for those activities should be more easily detected, monitored and arrested.
It has been recognized that coextruded multilayer films having a mismatch in refractive indices between adjacent polymer layers can be made to selectively reflect near infrared, visible or ultraviolet wavelengths of light. It has also been suggested that when designing a film to reflect in the infrared, it may be possible to suppress higher order reflections which might enter into the visible range, see, e.g., "Reflectivity of Iridescent Coextruded Multilayer Plastic Films," Radford, Alfrey, Jr., and Schrenk, Polymer Engineering and Science, vol. 13, 3 (May 1973): U.S. Pat. No. 3,247,392 to Thelen; and "Multilayer Filters with Wide Transmittance Bands," Thelen, Journal of the Optical Society of America, vol. 53, 11 (1963). It has been further recognized that altering the overall thickness of such a multilayer film will alter the apparent color or selective reflectivity of such films, see U.S. Pat. No. 4,094,947 to Alfrey, Jr., et al.
The extension of these ideas to create a multilayer film indicator for indicating the integrity or authenticity of an item or its conformance to an original state has not been suggested where the indicator includes a laminate having closely adjacent layers of two or more diverse thermoplastic materials of differing refractive indices associated with the item and having an identifiable original quality arising from the optical interactions of these layers of diverse materials. More specifically, such a multilayer film indicator has not been suggested which in an initial condition is substantially colorless but which has an identifiable original reflectance spectrum, and which produces and retains evidence of strain of a selected extent and greater which is not visible to the naked eye of an observer.
In view of the shortcomings of the prior art, both with specific regard to the previously known tamper evident, tamper resistant packaging materials and generally to indicators of the integrity or authenticity of an item or its conformance to an original state generally, it can be seen that there is a compelling need for such an indicator and for such a packaging material that do not alert one who would tamper with or counterfeit an item of the indicator's existence either before, during or after the tampering has taken place, that provides a safe and reliable means for detecting attempts at tampering or counterfeits, and that, moreover, is relatively inexpensive while being difficult to defeat, duplicate or replace.